Tomorrow could be worse with forecast temp at 34C for Prossy and very high humidity. Mt Julian AWS hit 46C on the heat index - yeah it was very oppressive. Looking though the Mt Julian records during 2016, the HI went higher that 50C five times during Jan and Feb!

Dew point temperature is closely tied to relative humidity. If air is at dew point temperature, the relative humidity is 100%. In other words dew point temperature is the temperature at which the air cannot absorb any more water and therefore water vapour begins to condense into fog and/or dew (condensation).

Relative humidity is the percentage saturation of water in the air at a specific temperature and pressure, so if a given volume of air at 25deg with a RH of 65% then increases to 30deg, the RH decreases (assuming no other changes occur). This is why dew that has collected on the ground in the early morning soon evaporates again as the temperature increases, because the air is then able to absorb more water.

When the relative humidity is very high and the air temperature is also high (like today), this results in the dew point being high as well because the air is close to being saturated with water.